1. Field of the Invention
The present invention relates to a method of manufacturing a thin film transistor array substrate. More particularly, the present invention relates to a method of manufacturing a thin film transistor array substrate having a reduced number of mask processes.
2. Discussion of the Related Art
A liquid crystal display adjusts light transmittance of liquid crystals using an electric field to thereby display an image. The liquid crystal display drives the liquid crystals by an electric field generated between a pixel electrode and a common electrode.
The liquid crystal display includes a thin film transistor (TFT) array substrate and a color filter array substrate that are positioned opposite each other and are attached to each other, a spacer that is positioned between the two array substrates to keep a cell gap between the two array substrates constant, and a liquid crystal layer filled in the cell gap.
The thin film transistor array substrate includes a plurality of signal lines, a plurality of thin film transistors, a plurality of pixel electrodes, and an alignment layer coated for an orientation of the liquid crystals. The color filter array substrate includes a color filter for a color representation, a black matrix for preventing a light leakage, a common electrode, and an alignment layer coated for an orientation of the liquid crystals.
The thin film transistor array substrate is typically manufactured using a plurality of mask processes including a semiconductor process. One mask process includes a large number of processes such as a thin film deposition process, a cleansing process, a photolithography process, an etching process, a photoresist peeling process, and a testing process. Thus, an increase in the number of mask processes results in an increase in the manufacturing cost of the liquid crystal display. Accordingly, an efforts to reduce the number of mask processes in the manufacture of the thin film transistor array substrate have been continuously made. The number of mask processes has recently been reduced to three (i.e., 3-mask process) through various processes such as a lift-off process.
However, the number of mask processes still needs to be reduced to be equal to or less than two (i.e., 2-mask process) so as to further reduce the manufacturing cost of the liquid crystal display.